Lotfe7u

[N.Ishigaki]

Lotfe7 was widely used on many Luftwaffe bombers.

A He343 drawing in the "Luft 46" website shows "Lofte7u" was to used.
http://www.luft46.com/heinkel/he343-6.gif

The "u" type is quite unfamiliar to me.What is the difference?

If there are any good references about the Luftwaffe bomb sight type
and variations, I'd like to read.

Several websites, such as wikipedia, describe about the variation,
Lotfe7, 7A to 7K-2 existed and applied to which aircraft, but not
mention the difference of them.